#include <iostream>
#include <cstring>
#define maxn 110
using namespace std;

int main()
{
	char s[1000];
	int len=0,i=0;
	while((s[len]=getchar())!='\n')
		len++;
	len--;
	while(s[i]==s[len-i])
		i++;
	if(i>len/2) cout<<"iopyes";
	else cout<<"no";
	return 0;
}
